A follow-up of 96 patients with Perthes' disease was made 28-47 years after onset of the disease. We paid special attention to leg-length inequality and its consequences and low-back disability. Leg-length inequality was a common finding, but low-back pain was not a significant problem. Leg-length inequality and lumbar scoliosis correlated poorly with low-back disorders. Degeneration of the lumbar spine was the only factor that correlated well with low-back pain.